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Resistance of wires

Extracts from this document...

Introduction

Syed Jafri ~ 11 East ~ Mr. I. Jackson ~

14 July 2006

Physics Coursework ~ Resistance Of Wires

Aim

        The aim of my coursework is based on scrutinising the factors which are responsible for affecting the resistance of a wire in an electrical circuit. I will write a report on a practical I carried out on how the factors affecting the resistance of a wire end up altering the potential difference and current flowing in the circuit.

What Is Resistance?

The standard opinion of resistance, when electricity is concerned, is the ability of a substance or material to resist the flow of electricity through it. Good conductors are associated with low resistance and poor conductors are associated with high resistance. As resistance is responsible for the current that flows, a high resistance will be responsible for a low current, and, vice-versa, a low resistance will be responsible for a higher current.Resistance is a force which opposes the flow of an electric current flowing around a circuit. This is why a more forceful energy is required to push the charged particles around the circuit (from the power supply).

        The approved definition for resistance, written in the Hutchinson encyclopaedia that I possess, is:

        “In physics, that property of a conductor that restricts the flow of electricity through it, associated with the conversion of electrical energy to heat; also the magnitude of this property. Resistance depends on many factors, such as the nature of the material, its temperature, dimensions, and thermal properties; degree of impurity; the nature and state of illumination of the surface; and the frequency and magnitude of the current. The SI unit of resistance is the ohm (Ω).”

Resistance is measured in Ohms (Symbol=Ω) for the reason that the name person who discovered resistance was George Ohm. He discovered that

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Middle

before switching the power pack on. All other experimental safety precautions will be applied.

Fair Testing ~

                In any case, and for every case, the investigational conditions must be kept unchanged. By this I mean to say that the temperature of the wire, state of illumination on the wire, power output from power pack, etc. must be the same for every different length of wire we test. So if the lights and the heating system in the room were switched on during the testing of the first wire, they both must be on for every test so that the change in the results is not massively different.

I will especially take the situations of recording results and measurement of wire very importantly, as a measurement error could lead to an irregular result. We must make sure that the electricity emerging from the power supply is exactly the same with every length of wire we test.

There should also be no mistake in investigating the correct material of wire each time, as a similar looking wire could easily be attached by mistake.

As the resistance will be calculated according to the length of wire, the length will increase by the same amount each time so that it is measured evenly. And each length will be experimented twice so that the results are verified and we are also reconfirmed that our practical was reliable.

Preliminary Experimentation

        The only material I used was copper, as it is a reasonable wire. So, as an introductory experiment, I attached 10cm length of copper wire first and recorded the resistance; and then 20cm length of copper wire after that (increasing by 10cm) and noted the results.image00.png

Length

Resistance

10cm

0.834Ω

20cm

1.661Ω

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Conclusion

crocodile clips. These connectors are weak and also are not reliable as the clip may decrease the length of wire that actually conducts the electricity. In order to solve this setback, there should be an alternate and effective way to measure and connect the subject wire. As I am talking about the wire, its material might have also had impurities and might have caused slight imperfection and disagreement.

        The temperature might have also caused the inaccuracy of actual resistance as the current passed through it, but that was not noticeable as the affect was so minute.

        There are some arguments throughout the practical of the experiment not being perfect, but the conclusion of the investigation was efficient and dependable. The experiment itself provides evidence that this practical was capable for calculating the resistance of a wire, even though there are some disapproving technicalities (which were previously clarified). The basic bottom line is that, for the accomplishment of working out that “the length of wire is proportional to the resistance of it”, this practical was a brief, uncomplicated and efficient investigation. There is no doubt that the conclusion and outcomes are authentic.

        If we put aside the disapproval of procedure (stated above in the evaluation), this investigation entirely supports my prediction and, most importantly, was a success!

The Resistance Of A Wire Is Proportional To The Length Of It

Extended Investigations

Any extended investigations could be like experimenting how the temperature, thickness and material affect the resistance of a wire. These few experiments could have been done with the same setup and would not need additional equipment.

...read more.

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